Many applications require glass that has been strengthened, for example in consumer and commercial electronic devices such as LCD and LED displays, computer monitors, automated teller machines (ATMs) and the like. Various processes may be used to strengthen the glass, including chemical tempering, thermal tempering, and lamination.
For example, in an ion exchange strengthening process, ions in the surface layer of the glass are replaced by, or exchanged with, larger ions in a bath solution (such as a salt bath) having the same valence or oxidation state. Lamination mechanical glass strengthening is a mechanism whereby two or more layers of glass having different coefficients of thermal expansion (CTE) are bonded or laminated. For example, in a laminate of three layers, i.e. a core layer surrounded by two clad layers, the relatively higher CTE of the core glass layer compared to the CTE of the clad glass layers causes the core glass layer to contract or shrink more than the clad glass layers upon cooling following thermal bonding. This causes the core glass layer to be in a state of tension and the clad glass layers to be in state of compression. The compressive stresses in the clad glass layers inhibit fracture formation and fracture propagation in the clad glass layers, thereby strengthening the glass laminate compared to clad glass that is not under compressive stresses. The laminate may also be thermally tempered to increase the compressive stress in the clad glass.
The manufacture of glass with increasingly higher strength poses challenges where cutting and separation of such glass is desired. Conventional glass cutting and separating methods, such as the use of score wheels for cutting and lasers and microwaves for separating, may not be sufficient for certain strengthened glass. For example, the use of score wheels employs a method whereby an indentation is created in the glass surface and the indentation is used to break or separate the glass along a path corresponding to the indentation. Applying pressure with a scoring wheel to create indentations in the strengthened glass surface has drawbacks, however, as the score wheels wear-out, which increases costs, and may even damage the glass or severely limit the edge strength of the glass once separated.
As such, it would be advantageous to provide new apparatuses and methods for scoring glass, for example strengthened glass articles such as laminate glass sheets.